The two specific things would be working in an non-sustainable industry (steel after tariffs, Enron, Mortgage-Backed Securities in 2007, GM today, etc.) If you company makes real money selling something people actually want, you're in decent shape.

As for paper investments, well, you are diversified into precious metals, and that's good. With a mortgage of 304K, I'd want more than 8K saved up in cash, but that's just me.

I might shift a few more $$ over to pay the house off in advance and take a hard look at what those funds are invested. (What happened to them in fall 2008?)

Otherwise, I'd say you're doing well. If you want a book to look at disruptive change, I'd suggest "The Black Swan." By Talib.